Diabetes mellitus is known to affect at least 10 million Americans, and millions more may unknowingly have the disease. In the form of this disease known as Type II, non-insulin dependent or adult-onset (as opposed to juvenile diabetes or Type I), the pancreas often continues to secrete normal amounts of insulin. However, this insulin is ineffective in preventing the symptoms of diabetes which include hyperglycemia, impaired carbohydrate metabolism, glycosuria and decreased insulin sensitivity. These symptoms, if left untreated, often lead to severe complications.
Current drugs used for managing Type II diabetes fall within two classes of compounds: the biguanides and the sulfonylureas. The biguanides, e.g. metformin, are believed to prevent excessive hepatic gluconeogenesis. The sulfonylureas, e.g. tolbutamide and glyburide, lower plasma glucose primarily by stimulating insulin secretion, by enhancing insulin effects in some target tissues and by inhibiting hepatic glucose synthesis.
U.S. Pat. No. 4,315,927 discloses that when selected essential metals are administered to mammals as exogenously synthesized coordination complexes of picolinic acid, they are directly available for absorption without competition from other metals. These complexes are safe, inexpensive, biocompatible and easy to produce.
U.S. Pat. No. 5,087,623 describes the administration of chromic tripicolinate for the treatment of Type II diabetes in doses which provide between 50 and 500 .mu.g of chromium. The U.S. Recommended Daily Allowance for chromium is 50-200 .mu.g. Although a small decrease in glycosylated hemoglobin, an accurate indicator of blood glucose levels, was observed, the 10.4% value obtained after chromic tripicolinate treatment was still will within the diabetic range.
International Patent Application No. PCT/US96/06493 discloses the administration of high ("supranutritional") doses of chromium (1,000 to 10,000 .mu.g/day) to individuals with Type II diabetes. Individuals who received 1,000 .mu.g chromium per day as chromic tripicolinate exhibited a 30% decrease in glycosylated hemoglobin and a similar reduction in fasting and postprandial glucose levels.
Biotin is the prosthetic group for a number of carboxylation reactions, the most notable being pyruvate carboxylase which is involved in gluconeogenesis and replenishment of the citric acid cycle, and acetyl CoA carboxylase which plays a role in fatty acid biosynthesis. The safe and adequate recommended daily intake of biotin is 100-300 .mu.g, although no side effects or toxicities were noted in previous clinical studies with oral biotin intakes of up to 200 mg daily (Mock et al, in Present Knowledge in Nutrition, seventh edition, Ziegler, E. et al., eds., ILSI Press, Washington, D.C., 1996, pp. 220-235). Supranutritional doses of biotin have been shown to have therapeutic utility in diabetes. High-dose oral or parenteral biotin has been shown to improve oral glucose tolerance in diabetic KK mice (Reddi et al., Life Sci., 42:1323-1330, 1988), rats made diabetic by injection with streptozotocin (Zhang et al., 16th International Congress of Nutrition, Montreal, 1997, abstract book, p. 264) and in pre-diabetic Otsuka Long-Evans Tokushima Fatty rats (Zhang et al., J Nutr. Sci. Vitaminol. 42:517-526, 1996).
In a clinical study, Coggeshall et al. (Ann. N.Y. Acad. Sci, 447:387-392, 1985) demonstrated that a daily oral dose of biotin of 16 mg lowered fasting plasma glucose levels in Type I diabetics in whom insulin injections had been temporarily discontinued. Maebashi et al. (J Clin. Biochem. Nutr. 14:211-218, 1993) showed that administration of 3 mg biotin three times per day to poorly-controlled type II diabetics resulted in improved pancreatic beta cell function as evidenced by the fact that fasting insulin levels did not decline in biotin-treated subjects despite the sharp decline in glucose levels.
There is a constant need for effective treatments for type II diabetes. The present invention addresses this need by providing a safe, inexpensive, drug-free therapeutic agent.